Wall Decor

In my house I have two walls that need some help. One is in the living room over the sofa (between two lamps) and the other is in the guest bedroom that right now... is just left overs with a new chair. Husband and I made a trip to I.KEA this weekend and I pointed out the things I would like to do over the couch. His ideas did not match up exactly with mine. I suggested shelves....

He prefers off center, different lengths, and different heights. Now, this picture probably doesn't cover how different he wants his shelves to be, but I thought it gave me (and him) a good visual.

I picture something with evenly placed shelves all of the same length. Some with pictures...some with other stuff.

But the shelves are only an alternative to wall collage trend. I really like the idea of gathering a punch of miss matched size objects and throwing them all together in a nice pleasing way.

This pretty much exactly, but my couch is much larger, so the collage would be wider instead of taller.

So what do you think? trendy or something I should try?